Combined scaffold bracket and lock



Sept. 30, 1958- H. J, RlBLET 2,854,293

COMBINED SCAFFOL D BRACKET AND LOCK Filed Oct. 26, 1953 2 Sheets-Sheet 1INVENTOR HENRY J. RIBLET Sept. 30, 1958 H. J. RIBLET comma SCAFFOLDBRACKET AND LOCK 2 Sheets-Sheet 2 Filed Oct. 26, 1953 FIG. 5

FIG. 5

7 V/VTOR HENRY J. RIBLET Unite tates The present invention relatesgenerally to platform supports of the class which painters and otherworkmen combine with a suitable upright to form a scaffold readilyadjustable in height, and more particularly, it relates to a combinedplatform support and automatic lock suitable for use on uprights formedof material having a low coelficient of friction, as for example,aluminum, and which may be readily and safely lowered without the use ofblock and tackle or other cumbersome rigging.

It is an object of my invention to provide a combined platform supportand automatic lock which may be lowered by a crank by one or moreworkmen while on the platform, but which, at the same time, isparticularly advantageous by virtue of the high degree of safetyinherent in its design whereby the only force required to preventaccidental failure and injury to the workman is provided by his ownweight.

It is a further object of my invention to provide a combined platformsupport and automatic lock which will lock safely at any position on ametal upright, but which is so contrived that the locking mechanism doesnot in any way wear the upright during its travel up and down the metalupright.

Other and further objects, advantages and features of the invention willbecome apparent as the description proceeds.

The present application is generally related to and constitutes animprovement and modification of my earlier invention described in U. S.Patent 2,342,427. This patent discloses means whereby the safe operationof a platform support and automatic lock may be made to depend only onthe weight of the operator whose safety is involved, and does notrequire springs or counter weights. The soundness and validity of theconcept underlying that invention have been amply demonstrated by thethousands of man hours of satisfactory service which scaffoldingemploying this invention have given in areas where other adjustablescaffoldings are banned as hazardous.

Briefly, my earlier patent disclosed a platform support which comprisedone or more U-shaped metal bands, each embracing an associatedrectangular upright, and each freely pivoted about a fulcrum in thesupport structure. A pair of cylindrical jaws extending through thesidewalls of each band and disposed on opposite sides of the uprightprovided an automatic lock, operative under the platform load topreclude unintended vertical motion. However, despite the advanceachieved by substantially eliminating accidents due to mechanicalfailure or human error, it was still necessary to use block and tackleto raise and lower the platform held in position by the automaticlocking supports.

In the present invention, I replace one of the jaws in the basicautomatic lock disclosed in the cited prior patcut, by a serrated bar orserrated roller freely rotatable relative to the U-shaped jaw supportingband. It is clear that such a freely rotating member would ordinarily bea source of danger unless additional provisions were ice made to preventinadvertent rotation. This is done by mounting it so that thelongitudinal axis of the roller jaw is eccentric relative to its bearingholes in the U- shaped supporting band, so that effectively, the spacingbetween the two jaws in each lock is a function of the angular positionof the serrated jaw which is free to rotate. Further, the separationbetween the jaws is so chosen relative to the size of the upright thatwhen the spacing between the inner and outer jaws is a maximum, theouter jaw is below the horizontal plane containing the fulcrum or in it.Thus, in all other positions possible as the serrated jaw rotates, theouter jaw assumes a lower, unstable position. Thus, these positions arepossible only by the deliberate efiort of the operator. He maydeliberately lower the outer jaw by depressing the automatic lock, or inone version of my invention, he may rotate the rotatable jaw by means ofa crank provided for this purpose, in which case the entire platformsupport structure lowers in a smooth, completely con trolled manner.

A more comprehensive understanding of this invention will be afforded bythe following detailed description considered in conjunction with theaccompanying drawings, and those features of the invention which arebelieved to be novel and patentable will be pointed out in the claimsappended hereto.

In the drawings:

Figure 1 is a side view of my invention in which part of the upright isshown, together with the end of the platform. A crank for rotating theeccentric jaw is also shown.

Figure 2 is a perspective view showing the U-shaped member which,together with the fulcrum and two jaws, one rotatable by means of acrank, constitute the central part of my invention.

Figure 3 is a side view of a portion of the platform supporting frameand a portion of the upright together with the automatic lock which isshown with the eccentric rotatable jaw in the position of stableequilibrium where the lock cannot be lowered without the consciouseffort of the operator.

Figure 4 is a side view of a similar portion of my invention in whichthe outer portion of the automatic lock has been lowered, perhaps by aworkman turning the crank, to an unstable position which is encounteredduring the deliberate lowering of the platform supporting bracket.

Figure 5 is a similar view of Figure 3 in which the inner jaw of theautomatic lock is eccentrically rotatable.

Figure 6 is a view similar to Figure 4 in which the inner jaw iseccentrically rotatable. This is an unstable position of the automaticlock which will be encountered in raising and lowering the adjustableplatform supporting bracket.

Throughout these views, like reference numerals will be used whereverapplicable and they will be chosen as far as possible to correspond tothose of U. S. Patent 2,342,427 which has been referred to previously.

With reference now to the drawings, and more particularly to Figures 1and 2 thereof, the character 1 denotes an upright which is embraced bythe U-shaped band 2, and the automatic lock 3. The automatic lockcomprises the U-shaped portion 4, an inner jaw 6 and an outer jaw 5. Thelock is free to rotate about a fulcrum 7, provided simply by a bolt andnut. The open portion of a U-shaped member 2 is held apart by aseparator 8 upon which there freely rolls a sleeve 10. The bolt 11 whichsecures the open end of U-shaped member 2 also carries an obliquediagonal support 12 and a substantially vertical support 13. Bothsupports 12 and 13 carry a horizontal member 14, to which they arerespectively fastened by bolts 15 and 7. Platform 16 is carried byhorizontal'member 14, and prevented from slipping by the extension onthe upper end of diagonal bar 12.

In Figures l-4, the outer jaw is free to rotate in bearing holesprovided in the U-shaped member 4. Fig- 'ure 2 shows how'the outer jaw 5is provided with serrations or irregularities for gripping upright 1. Ifthis upright is metallic, these serrations may be hardened for longerlife. In Figures 5-6, it is the inner jaw 6' which is free to rotatewhile the outer jaw 5' is fixed.

serrations are cut and which contacts the vertical upright does notcoincide with the line joining the centers of the bearing holes providedin the U-shaped member 4 in which the reduced diameter eccentric ends ofthe rotating jaw 5 or 6' rotate. This displacement of the two lines mayvary from .010" to .125 in practical embodiments and is not particularlycritical, and is clearly shown in all of the figures.

In Figures 1-4, the rotating jaw 5 is provided with an integral crankextension '18 by which the jaw 5 can be caused to rotate and which canbe used as will be explained to lower the platform supporting bracket.In

Figures 5 and 6, no crank is shown. This latter arrangement appears tobe preferable when the vertical upright is metallic, and the position ofthe platform supporting bracket is controlled by a rope and pulleysystem as shown in the patent already referred to.

U. S. Patent 2,342,427 has taught the principle that an automatic lock,consisting of a band supported on a fulcrum and having inner and outerjaws, has as its only stable position its locked position wherein theouter jaw lies substantially in the same horizontal plane or lower thanthe fulcrum, while the inner jaw is substantially lower; and is unstablein any unlocked position, provided that some load is available on theplatform supporting bracket.

The present invention teaches that one or both of these jaws may befreely rotatable so long as the rotation is eccentric and for noposition of the rotatable jaw does the outer jaw rise above thehorizontal plane containing the fulcrum. This point will be demonstratedwhen it is shown that once the outer jaw has obtained its position ofmaximum height relative to the fulcrum, that the rotating jaw is nolonger free to rotate and may be considered fixed.

Consider Figure 3 in which the outer jaw 5 is free to rotateeccentrically with respect to the axis of its supporting holes. Theeccentric rotating jaw 5 is illustrated in the position where thelongitudinal axis of the serrated cylindrical surface is in the samehorizontal plane as the center of the supporting holes 19, but isdisplaced farther from the vertical upright 1. Also, the distancebetween the inner jaw 6 and outerjaw 5 has been chosen so that thefulcrum 7 and inner jaw 5 lie substantially in the same horizontalplane. It is now clear that any rotation of the outer jaw 5 must resultin a tipping of the automatic lock 3 as shown in Figure 4. Thisposition, however, as'we have seen, is unstable when the platform isloaded. Thus, the automatic lock 3 will return to the position of Figure3 as soon as the platform supporting bracket attempts to move downward.

In the locked position of Figure 3, the outer jaw 5 will not rotatemerely under the influence of a load, and thus, the inner jaw 6 land theeccentric rotatable jaw 5 will cooperate to support the platformsupporting bracket if they are properly spaced relatively to each other,and sufficient friction exists between them and the vertical upright. Inthe event that the vertical upright 1 is metallic, sufiicient frictionto prevent slipping may be insured by providing the rotating jaw 5 or 6with serrations 5a, as shown in Figure 2.

To-insure that the slideable bracket may be freely lowered, when therotating eccentric jaw 5 has rotated to the position where its axis isin the, same horizontal plane as the centers of the supporting holes 19,but is displaced nearer the vertical upright as in Figure 4, therotating eccentric jaw 5 must be above the horizontal plane containingthe inner jaw 6. This insures that further lowering of the automaticlock 3 will release the inner jaw 6 from the vertical upright regardlessof the position of rotation of the eccentric rotating jaw 5.-

It will be clear to one familiar with the art that similar remarks canbe made concerning Figures 5 and 6, where the inner jaw.6' is free torotate eccentrically in bearing holes 19 provided in the U-shaped strap4. Figure 5 shows the position of the automatic lock 3 in the stablelocked position and Figure 6 shows how the automatic lock 3 may bedepressed, as-for example, by placing the heel on the upper end of theouter edge thereof, so that the inner jaw 6 will not grip the verticalupright 1.-

The eccentric rotating outer jaw 5 .of Figures 1-4 has been providedwith a crank 18. With this, a workman sitting or standing on platform 16can gradually lower the platform supporting bracket without any dangerof a sudden or accidental fall. All he has to do is to rotate the crank18 in a clockwise direction; If sufficient friction exists between theeccentric rotating jaw Sand the vertical upright 1, as can always beprovided by suitably serrating this jaw, this will force the outer jawdownward to a point where the friction between the inner jaw 6 and thevertical upright 1 is exceeded by the load and the force applied by thecrank, and the platform supporting bracket begins to descend. It isclear that the rate of descent cannot exceed that permitted by thecrank, since for all fixed positions of the crank, a stable lockedposition results. Moreover, if the crank were accidentally released bythe workman, the platform supporting bracket could at most fall to thestable locked position of Figure 3. In the event thatthe platformsupporting bracket is controlled by rope and pulleys as shown in myearlier invention, and the vertical upright is metallic, perhapsaluminum, the arrangement shownin Figures 5 and 6 is preferred. Althoughthe same general etfectfor this application could be achieved byserrating a fixed nonrotating jaw, such as "arrangement would tend towear the vertical upright, whereas when the serrations are placed on aneccentric rotating jaw as in the present invention, these serrationsnever tend to wear the upright, because they are always in rollingcontact, on the vertical upright whenever they are moving relative toit.

It will be evident from the foregoing description that I have provided acombined platform, supporting member and automatic lock which realizesthe objectives given earlier in the specification.

Various changes may be made in the specific embodiment' of the presentinvention without departing from the spirit thereof, or from the scopeof the appended claims. i

What isclaimed is: l. A scaffold locking device in combination withaplatform supporting frame and an upright, means connecting the lowerportion of said frame to said upright in slidable non-grippingrelationship, a lock, lock pivoting means for pivotally fastening saidlock to the upper portion of said frame, said lock being formed withvertically oflset outer and inner jaws, one of said jaws lying inner jawlower than said lock pivoting means, and so that in the unlockedposition said outer jaw bears against said upright and said. inner jawis spaced inwardlytaway from said upright and is farther below said lockpivoting means than when said lock was insaid locking position, onev ofsaid jaws comprising a cam freely and continuously rotatable with itssurface in continuous contact with said upright.

2. A scaffold locking device in combination with a platform supportingframe and an upright, said frame em bodying an upwardly extending memberadjacent to said upright, a laterally extending member and a diagonallyextending member connected to and extending between said other twomembers, a pin member at the junction of the lower portions of saidupwardly and diagonally extending frame m mbers, means securing said pinmember to said upright in non-gripping relationship, a lock, loci;pivoting means for pivotally fastening said lock at one end thereof tothe end of said laterally extending member adjacent said upright andconnected to said upwardly extending member, said lock being formed withouter and inner jaws so positioned relative to each other and to saidlock pivoting means that in the locking position, said outer jaw andlock pivoting means are substantially in horizontal alignment with saidouter and inner jaws bearing against said upright and with said innerjaw lower than said lock pivoting means, and so that in the unlockedposition, said outer jaw bears against said upright and said inner jawis spaced inwardly away from said upright and is farther below said lockpivoting means than when said lock was in said locking position, saidouter jaw comprising a cam formed with a serrated substantiallycylindrical outer surface, and a hand crank for rotating said outer jawabout an axis displaced from and parallel to the axis of its serratedcylindrical surface with the latter surface in continuous contact withsaid upright for raising and lowering said platform support ing frame.

3. In combination with a scaffold having an upright of generallyrectangular cross-section, a platform supporting frame, and means forattaching the lower end port on of said supporting frame to said uprightin a slideable non-gripping relationship; an automatic lock, saidantomatic lock comprising a pair of rigidly spaced sidewall membersembracing said upright, a pivot for pivotally joining said members tosaid frame, first and second parallel jaws formed with cylindrical outersurfaces extending between said members on opposite sides of saidupright, said second jaw being disposed on the side of said upright mostremoved from said pivot, said first jaw being disposed to bear againstthe side of said upright adjacent said pivot below both said pivot andsecond jaw, said second jaw comprising a cam continuously rotatableabout an axis displaced from and parallel to the axis of its cylindricalouter surface and arranged whereby during each complete revolution ofsaid cam with the surface thereof in continuous contact with saidupright, the spacing between said jaws cyclically varies between apredetermined minimum under which condition said pivot is raised abovesaid second jaw, and a predetermined maximum under which condition saidpivot and second jaw are disposed substantially in the same horizontalplane.

References fitted in the file of this patent UNITED STATES PATENTS138,385 Elliott Apr. 29, 1873 166,758 Fellows Aug. 17, 1875 431,745Haven July 8,1890 446,472 Roberts Feb. 17, 1891 618,510 Kail Jan. 31,1899 878,455 Carter Feb. 4, 1908 1,366,487 Pitou -2 Jan. 25, 19211,441,806 Hoitsma Jan. 9, 1923 2,038,899 Hoitsma Apr. 28, 1936 2,164,519Hayner July 4, 1939 2,342,427 Riblet Feb. 22, 1944 2,605,074 Bucsko eta1. July 29, 1952

